U.S. patent application number 09/525164 was filed with the patent office on 2002-07-18 for surveying system.
Invention is credited to Ishinabe, Ikuo, Muraoka, Yoshiaki, Takahashi, Sho-Ujiro.
Application Number | 20020093646 09/525164 |
Document ID | / |
Family ID | 26424459 |
Filed Date | 2002-07-18 |
United States Patent
Application |
20020093646 |
Kind Code |
A1 |
Muraoka, Yoshiaki ; et
al. |
July 18, 2002 |
SURVEYING SYSTEM
Abstract
The present invention provides a surveying system, which
comprises a survey instrument main unit for receiving and detecting
a guide light projected from a collimation target, a horizontal
rotating mechanism 38 for rotating the survey instrument main unit
in a horizontal direction, a control unit 37 for controlling the
horizontal rotating mechanism, a rough direction detecting unit 24
capable to detect the guide light from all horizontal directions,
and a precise direction detecting unit 25 arranged in a direction
to collimate the survey instrument main unit from a telescope and
detects said guide light only in a range of a predetermined angle,
wherein said control unit controls the horizontal rotating
mechanism so that a direction of the survey instrument main unit is
aligned to the collimation target based on a result of a detection
from said rough direction detecting unit, and collimates the survey
instrument main unit is collimated to the collimation target based
on a result of a detection from the precise direction detecting
unit.
Inventors: |
Muraoka, Yoshiaki;
(Tokyo-to, JP) ; Ishinabe, Ikuo; (Tokyo-to,
JP) ; Takahashi, Sho-Ujiro; (tokyo-to, JP) |
Correspondence
Address: |
Henry C Nields
Nields & Lemack
176 E Main Street Suite 8
Westboro
MA
01581
US
|
Family ID: |
26424459 |
Appl. No.: |
09/525164 |
Filed: |
March 14, 2000 |
Current U.S.
Class: |
356/141.2 |
Current CPC
Class: |
G01C 15/00 20130101 |
Class at
Publication: |
356/141.2 |
International
Class: |
G01C 001/00; G01B
011/26 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 1999 |
JP |
83434/1999 |
Dec 22, 1999 |
JP |
364155/1999 |
Claims
What is claimed is:
1. A surveying system, comprising a survey instrument main unit for
receiving and detecting a guide light projected from a collimation
target, a horizontal rotating mechanism for rotating the survey
instrument main unit in a horizontal direction, a control unit for
controlling the horizontal rotating mechanism, a rough direction
detecting unit capable to detect said guide light from all
horizontal directions, and a precise direction detecting unit
arranged in a direction to collimate the survey instrument main
unit from a telescope and detects said guide light only in a range
of a predetermined angle, wherein said control unit controls said
horizontal rotating mechanism so that a direction of said survey
instrument main unit is aligned to said collimation target based on
a result of a detection from said rough direction detecting unit,
and collimates said survey instrument main unit to said collimation
target based on a result of a detection from said precise direction
detecting unit.
2. A surveying system according to claim 1, wherein said precise
direction detecting unit comprises a photodetection sensor, a
photodetection limiting means for limiting a photodetection range
in a horizontal direction of said photodetection sensor, and an
optical means for converging said guide light at a position of the
photodetection limiting means.
3. A surveying system according to claim 2, wherein said optical
means is a cylinder lens.
4. A surveying system according to claim 2, wherein said optical
means is a cylinder lens curved around a focal point thereof.
5. A surveying system according to claim 2, wherein said
photodetection limiting means is a mask arranged on a
photodetection surface of said photodetection sensor.
6. A surveying system according to claim 2, wherein said
photodetection limiting means is a diaphragm plate arranged at a
focal point of said optical means.
7. A surveying system according to claim 2, wherein said
photodetection limiting means further comprises a front stage
diaphragm for cutting off reflection lights in said precise
direction detecting unit.
8. A surveying system according to claim 7, wherein said front
stage diaphragm has a plurality of slits with size thereof
gradually reduced toward a photodetection surface.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a surveying system for
searching a target and for automatically performing a
collimation.
[0002] The survey operation is performed using a survey instrument
positioned at a reference point and a collimation target (a
reflection mirror, a corner cube, etc.) installed at a target point
which is to be collimated by the survey instrument.
[0003] With the progress in an automation technique, the survey
instrument is also under the influence of such a trend, and a
survey operation is now generally practiced by an one-man
operation.
[0004] A survey instrument thus automated comprises an angle
detector for measuring a direction of the collimation, and a light
wave survey instrument for measuring the distance to a collimation
target. Further, in order to achieve the survey operation under
one-man control, it is provided with a tracking function for
detecting and tracking the collimation target. In the survey
operation under one-man control, an operator is positioned on
collimation target side, and the collimation target is moved by the
operator depending on a working process. When the operator moves
the collimation target, the survey instrument tracks the
collimation target and automatically collimates the collimation
target.
[0005] Once the survey instrument has collimated the collimation
target, the collimation target is automatically tracked. In this
case, the range of collimation is limited to a range of visual
field of a telescope of the survey instrument. Therefore, when the
collimation target is moved, and if the collimation target is moved
at such speed that tracking can be performed, tracking can be
carried out without any problem. However, if the moving speed is
higher than the speed, at which tracking can be performed or in
case the collimation target is beyond the visual field of the
telescope, tracking cannot be performed. Or, in case the visual
field is temporarily interrupted by some obstacle, no tracking can
be carried out. When tracking cannot be performed, similarly to the
case where the collimation target is collimated for the first time,
the survey instrument is rotated approximately over total
circumference to search the collimation target.
[0006] To search the collimation target, the survey instrument is
rotated over total circumference, and a reflection beam of the
laser beam from the survey instrument reflected by the collimation
target is detected by the survey instrument.
[0007] When the survey instrument searches the collimation target,
the reflection beam from the collimation target must be detected by
the telescope. However, the visual field of the telescope is
narrow, and the survey instrument main unit must be rotated
repeatedly over total circumference while changing the vertical
angle. It is necessary to frequently perform the searching of the
collimation target, not only in the first collimation in the survey
operation but in the middle of surveying process from the reasons
as described above. Because it takes much time for the searching of
the collimation target at present, it is very important to search
the collimation target within short time and in an efficient manner
in order to increase working efficiency in the survey operation
under one-man control.
[0008] When we consider the guide light entering the survey
instrument, not only the guide light directly entering from the
collimation target, but also the guide light reflected by an
optical system after entering the survey instrument is included in
it. Further, the light other than the guide light is also included.
The light and beam reflected by the optical system is turned to
noise, and S/N ratio is decreased. When S/N ratio is low or when
S/N ratio is changed due to the light receiving condition, an
amplification factor of a photodetection signal from a
photodetection element must be changed to an optimal value. This
causes such a problem that much time is required for the searching
of the collimation target.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide a
system, by which it is possible to promptly detect a collimation
target without rotating the survey instrument main unit over total
circumference and to perform the searching of the collimation
target within short time and in efficient manner. It is another
object of the present invention to provide a system, by which it is
possible to improve S/N ratio of the received reflection beam and
to perform the collimation of the collimation target within the
shortest time.
[0010] To attain the above objects, the surveying system according
to the present invention comprises a survey instrument main unit
for receiving and detecting a guide light projected from a
collimation target, a horizontal rotating mechanism for rotating
the survey instrument main unit in a horizontal direction, a
control unit for controlling the horizontal rotating mechanism, a
rough direction detecting unit capable to detect the guide light
from all horizontal directions, and a precise direction detecting
unit arranged in a direction to collimate the survey instrument
main unit from a telescope and detects the guide light only in a
range of a predetermined angle, wherein the control unit controls
the horizontal rotating mechanism so that a direction of the survey
instrument main unit is aligned to the collimation target based on
a result of detection from the rough direction detecting unit, and
collimates the survey instrument main unit to the collimation
target based on a result of a detection from the precise direction
detecting unit. Further, the present invention provides a surveying
system as described above, wherein the precise direction detecting
unit comprises a photodetection sensor, a photodetection limiting
means for limiting a photodetection range in a horizontal direction
of the photodetection sensor, and an optical means for converging
the guide light at a position of the photodetection limiting means.
Also, the present invention provides a surveying system as
described above, wherein the optical means is a cylinder lens.
Further, the present invention provides a surveying system as
described above, wherein the optical means is a cylinder lens
curved around a focal point thereof. Also, the present invention
provides a surveying system as described above, wherein the
photodetection limiting means is a mask arranged on a
photodetection surface of the photodetection sensor. Further, the
present invention provides a surveying system as described above,
wherein the photodetection limiting means is a diaphragm plate
arranged at a focal point of the optical means. Also, the present
invention provides a surveying system as described above, wherein
the photodetection limiting means further comprises a front stage
diaphragm for cutting off reflection lights in the precise
direction detecting unit. Further, the present invention provides a
surveying system as described above, wherein the front stage
diaphragm has a plurality of slits with size thereof gradually
reduced toward a photodetection surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a general schematical view of an embodiment of the
present invention;
[0012] FIG. 2 is a perspective view of a survey instrument main
unit in the above embodiment;
[0013] FIG. 3 is a plan view of the survey instrument main
unit;
[0014] FIG. 4 is a sectional elevation view of the survey
instrument main unit;
[0015] FIG. 5 is a block diagram of a projecting device provided on
a collimation target which is to be installed with respect to the
survey instrument;
[0016] FIG. 6 is a block diagram showing an essential portion of
the embodiment of the present invention;
[0017] FIG. 7 is a perspective view of an essential portion of a
precise photodetection unit of the embodiment of the present
invention;
[0018] FIG. 8 is a plan view of an essential portion of the precise
photodetection unit;
[0019] FIG. 9 is a diagram showing a photodetection signal from the
precise photodetection unit;
[0020] FIG. 10 is a perspective view of a precise photodetection
unit of a second embodiment of the present invention;
[0021] FIG. 11 is a side view of an essential portion of the
precise photodetection unit of the second embodiment;
[0022] FIG. 12 is a perspective view of an essential portion of a
precise photodetection unit of a third embodiment of the present
invention;
[0023] FIG. 13 is a plan view of an essential portion of a precise
photodetection unit of the third embodiment;
[0024] FIG. 14 is a side view of an essential portion of the
precise photodetection unit of the third embodiment;
[0025] FIG. 15 is a plan view of an essential portion of a precise
photodetection unit of a fourth embodiment of the present
invention;
[0026] FIG. 16 is a side view of an essential portion of the
precise photodetection unit of the fourth embodiment; and
[0027] FIG. 17 is a side view of an essential portion of a precise
photodetection unit of a fifth embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Description will be given below on embodiments of the
present invention referring to the drawings.
[0029] In FIG. 1, a survey instrument 2 is installed at a known
point A via a tripod 1. At a target point B, a pole 4 is erected,
and a collimation target 3 is attached on the pole 4.
[0030] As shown in FIG. 2 and FIG. 4, the survey instrument 2
comprises a base plate 6 mounted on the tripod 1, and a survey
instrument main unit 7, which is rotatably mounted around a
vertical axis on the base plate 6. The survey instrument main unit
7 comprises a base stand 8 and a telescope 9, which is rotatably
mounted around a horizontal axis on the base stand 8.
[0031] Inside the base stand 8, there is provided a horizontal
rotating mechanism 38, which rotates (horizontally) the survey
instrument main unit 7 around the vertical axis.
[0032] A horizontal rotation shaft 56 is rotatably supported on a
bearing unit 55 mounted on the base plate 6, and a housing 57 of
the base stand 8 is rotatably mounted on the horizontal rotation
shaft 56. A horizontal rotating gear 58 is fixed on the bearing
unit 55, and a horizontal rotation driving gear 59 is engaged with
the horizontal rotating gear 58. A horizontal rotating motor 60 is
provided inside the housing 57, and the horizontal rotation driving
gear 59 is fitted to the output shaft of the horizontal rotating
motor 60. A horizontal rotation detector 39 is provided with
respect to the horizontal rotation shaft 56. The horizontal
rotation detector 39 and the horizontal rotating motor 60 are
connected to a control unit 37, which is to be described later.
[0033] A vertical rotating mechanism 61 is arranged inside the base
stand 8.
[0034] The telescope 9 is rotatably supported on the housing 57 via
a vertical rotation shaft 62, and a vertical rotation gear 63 is
fitted to the vertical rotation shaft 62, and a vertical rotation
driving gear 64 is engaged with the vertical rotation gear 63. The
vertical rotation driving gear 64 is fitted to the output shaft of
a vertical rotating motor 65 provided inside the housing 57. A tilt
angle detector 66 is arranged to the vertical rotation shaft 62,
and the tilt angle detector 66 and the vertical rotating motor 65
are connected to the control unit 37.
[0035] When the survey instrument main unit 7 is rotated
horizontally by the horizontal rotating mechanism 38, the
horizontal angle is detected by the horizontal rotation detector
39. The telescope 9 is vertically rotated (tilted) by the vertical
rotating mechanism 61, and the tilt angle is detected by the tilt
angle detector 66.
[0036] Detection results of the horizontal rotation detector 39 and
the tilt angle detector 66 are inputted to the control unit 37, and
driving of the horizontal rotating mechanism 38 and the vertical
rotating mechanism 61 is controlled by the control unit 37.
[0037] A range-finding beam 11 is projected from the survey
instrument main unit 7 toward the collimation target 3. The
range-finding beam 11 is reflected by a reflection unit (a corner
cube 12) attached on the collimation target 3. The survey
instrument main unit 7 receives the reflection light beam from the
corner cube 12, and the distance between the known point A and the
target point B is measured.
[0038] The collimation target 3 comprises a projecting device 14
for projecting guide light 15 for tracking toward the survey
instrument 2.
[0039] Now, description will be given on the projecting device 14
referring to FIG. 5.
[0040] The projecting device 14 primarily comprises an operation
unit 16 arranged on the backside of the collimation target 3, and a
projection control 17. The projection control 17 comprises a CPU 18
for controlling light emission, an interface 19 for connecting the
CPU 18 with the control unit 16, a modulation circuit 23 to be
connected to the CPU 18, a driving circuit 20 for driving and
emitting a light emitting element 21 based on a signal from the
modulation circuit 23, and a projecting lens 22 for converging the
laser beam emitted from the light emitting element 21 and for
projecting the light beam as the guide light 15.
[0041] The survey instrument main unit 7 comprises a collimation
target searching means as to be described later. The collimation
target searching means detects the guide light 15 projected from
the projecting device 14 and collimates the survey instrument main
unit 7 to the collimation target at a position where the guide
light 15 is projected.
[0042] The collimation target searching means comprises a rough
direction detecting unit 24 and a precise direction detecting unit
25.
[0043] First, the rough direction detecting unit 24 will be
described in connection with FIG. 2, FIG. 3 and FIG. 6.
[0044] On four surfaces of the base stand 8 except upper and bottom
surfaces, photodetection units 26, 27, 28 and 29 are provided. All
of the photodetection units 26, 27, 28 and 29 are designed in the
same manner. In the following, description will be given only on
the photodetection unit 26, and no detailed description will be
given on the other photodetection units 27, 28 and 29.
[0045] The photodetection unit 26 essentially comprises a
photodetection window 31, a photodetection element 32, an electric
filter circuit 33, a demodulation circuit 34, and an A/D conversion
circuit 35.
[0046] A signal from each of the photodetection units 26, 27, 28
and 29 is inputted to a direction detecting arithmetic unit 36,
which detects the approximate direction depending on whether the
signal from the photodetection units 26, 27, 28 or 29 is strong or
weak, and the result of the detection is sent to the control unit
37. The control unit 37 drives a horizontal rotating mechanism 38
incorporated in the base plate 6 and turns the optical axis of the
telescope 9 toward the collimation target 3.
[0047] Now, the precise direction detecting unit 25 will be
described in connection with FIGS. 2, 3, 6, 7 and 8.
[0048] A precise photodetection unit 40 is provided on the surface
of the base stand 8, which faces in the same direction as the
surface where an objective lens of the telescope 9 is arranged. The
precise photodetection unit 40 comprises a cylinder lens 41, also
served as a photodetection window, a band-pass filter 42 allowing
to pass a wavelength range of the guide light 15, a photodetection
element 43 arranged on focusing a position of the cylinder lens 41,
a mask 45 arranged in such manner as to form a slit photodetection
surface 44 on the photodetection element 43, an electric filter
circuit 46, a demodulation circuit 47, and an A/D conversion
circuit 48. An axis of a convex surface of the cylinder lens 41 is
extended in a vertical direction and the lens converges the
entering guide light 15 in a horizontal direction. The electric
filter circuit 46, the demodulation circuit 47, and the A/D
conversion circuit 48 are designed in the same manner as the
electric filter circuit 33, the demodulation circuit 34, and the
A/D conversion circuit 35 as already described.
[0049] A photodetection signal of the precise photodetection unit
40 is inputted to the direction detecting arithmetic unit 36. When
the photodetection signal from the precise photodetection unit 40
is inputted, the direction detecting arithmetic unit 36 calculates
the direction of the collimation target 3 from the photodetection
signal. When the signal from the precise photodetection unit 40 is
inputted, the signal from the horizontal rotation detector 39 is
inputted to the control unit 37. Based on the signals from the
precise photodetection unit 40 and the signal from the horizontal
rotation detector 39, the control unit 37 determines the direction
of the collimation target 3. Then, the horizontal rotating
mechanism 38 is driven, and the collimating direction of the
telescope 9 is ultimately aligned on the collimation target 3.
[0050] In the following, description will be given on an
operation.
[0051] In case the survey operation is started or in case tracking
cannot be achieved during the survey operation, an operation mode
of the survey instrument 2 is turned to a searching mode.
[0052] The searching mode has two aspects, i.e. a rough direction
searching mode and a precise direction searching mode. First, the
collimation target 3 is searched in the rough direction searching
mode. In the rough direction searching mode, the direction
detecting arithmetic unit 36 can incorporate or receive a
photodetection signal from the rough direction detecting unit 24,
and a photodetection signal from the precise photodetection unit 40
is blocked.
[0053] The photodetection unit 26 of the rough direction detecting
unit 24 is provided on the same surface as the precise
photodetection unit 40, and the other photodetection units 27, 28
and 29 are provided on three different surfaces respectively.
Accordingly, the guide light 15 from the projecting device 14 is
received by at least one of the photodetection units 26, 27, 28 or
29. In case only one of the photodetection units 26, 27, 28 or 29
receives the guide light 15, the direction detecting arithmetic
unit 36 determines the rotating direction depending on the
photodetecting position. The survey instrument main unit 7 is
rotated via the horizontal rotating mechanism 38, and the direction
of the survey instrument main unit 7 is determined at a position
where the photodetection signal contains only the signal from the
photodetection unit 26. In case the photodetection unit 27 receives
the beam, for example, the survey instrument main unit 7 is rotated
counterclockwise. In case the photodetection unit 29 receives the
beam, it is rotated clockwise. In brief, it is designed in such
manner that only the photodetection unit 26 receives the guide
light 15 at the shortest distance.
[0054] In case two of the photodetection units 26, 27, 28 and 29
receive the guide light 15, photodetection intensity is
comparatively calculated at the direction detecting arithmetic unit
36. For example, when there are photodetection signals from the
photodetection units 26 and 27, the photodetection signals from the
photodetection units 26 and 27 are compared with each other, and it
is determined which of the photodetection units has higher
photodetection signal. Based on the intensity of the photodetection
signal, the direction detecting arithmetic unit 36 determines a
rotating direction of the horizontal rotating mechanism 38. For
example, if the photodetection signal from the photodetection unit
26 is higher, which is arranged on the same surface as the surface
where the precise photodetection unit 40 is arranged, the direction
detecting arithmetic unit 36 drives the horizontal rotating
mechanism 38, and the survey instrument main unit 7 is rotated in
such direction that the photodetection signal from the
photodetection unit 26 becomes higher, i.e. in the counterclockwise
direction in FIG. 3. In this case again, it is designed in such
manner that only the photodetection unit 26 receives the guide
light 15 at the shortest distance.
[0055] To simplify the operation sequence, the rotating direction
of the survey instrument main unit 7 by the horizontal rotating
mechanism 38 in the searching mode may be determined to one
direction. In this case, when the survey instrument main unit 7 is
rotated in a predetermined direction by the horizontal rotating
mechanism 38 and the signal from the rough direction detecting unit
24 is turned to the signal from the photodetection unit 26 only,
the rough direction searching mode is terminated.
[0056] When the rough direction searching mode is terminated, it is
in such condition that the photodetection unit 26 is facing to the
collimation target 3 so that the photodetection signals from the
photodetection units 27, 28 and 29 except the signal from the
photodetection unit 26 are negligible. Therefore, the direction of
the survey instrument main unit 7 is at least within the range of
.+-.45.degree. with respect to the correctly collimated state.
[0057] When the rough direction searching mode is terminated, it is
turned to the precise direction searching mode.
[0058] In the precise direction searching mode, the horizontal
rotating mechanism 38 is reciprocally rotated within the range of
.+-.45.degree.. The direction detecting arithmetic unit 36
incorporates the signal from the precise photodetection unit 40 and
blocks the signal from the rough direction detecting unit 24. As
the survey instrument main unit 7 is rotated, the guide light 15
enters through the cylinder lens 41 during rotation.
[0059] The cylinder lens 41 converges the guide light 15 to a
horizontal direction and the light is projected as linear light to
a photodetection surface of the photodetection element 43. The
band-pass filter 42 allows to pass the wavelength range of the
guide light 15 and cuts off the other disturbance light. As a
result, the photodetection element 43 can receive the guide light
15 with high S/N ratio.
[0060] Because the photodetection surface of the photodetection
element 43 is covered by the mask 45 except the slit photodetection
surface 44, the photodetection element 43 issues a photodetection
signal only when the linear guide light 15 projected passes through
the slit photodetection surface 44. FIG. 9 is a diagram showing a
photodetection signal from the photodetection element 43 except
disturbance light. A width of the slit photodetection surface 44 is
set in such manner that the photodetection range is .+-.1.degree..
That is, the guide light 15 can be received within the range of
.+-.1.degree..
[0061] The direction detecting arithmetic unit 36 calculates a peak
value of the photodetection signal from the precise photodetection
unit 40 or calculates a weighted position of the entire
photodetection signal. At the peak value of the photodetection
signal, i.e. at the weighted position, the direction of the optical
axis of the telescope 9 is aligned with the direction of the
optical axis of the guide light 15 of the collimation target 3. The
control unit 37 incorporates an angular signal of the horizontal
rotation detector 39 at the peak value of the photodetection signal
and at the weighted position, and a horizontal angle is determined,
at which the telescope 9 accurately collimates the collimation
target 3. When the horizontal angle is determined, the control unit
37 drives the horizontal rotating mechanism 38 and rotates the
survey instrument main unit 7 so that the angle detected by the
horizontal rotation detector 39 is turned to the determined
angle.
[0062] When the collimation is completed, the operation mode of the
survey instrument 2 is turned to a tracking mode.
[0063] As described above, the photodetection element 43 can
receive the guide light 15 at the horizontal angle .+-.1.degree. of
the telescope 9. When the collimation target 3 moves within a range
not deviated from the horizontal angle .+-.1.degree., the survey
instrument main unit 7 tracks the collimation target 3, and the
collimation is promptly completed.
[0064] No specific description is given on the collimation in a
vertical direction of the telescope 9. The slit photodetection
surface 44 of the photodetection element 43 is divided into two
portions, i.e. upper and lower portions with the boundary at the
center, so that the photodetection signal can be obtained from each
of the divided photodetection surfaces. After the collimation in
the horizontal direction is completed, the vertical rotating
mechanism 61 is driven so that ratio of the photodetection signals
from the divided two photodetection surfaces is turned to 1, and
that the optical axis of the telescope 9 is aligned with the center
of the slit photodetection surface 44.
[0065] As described above, to search the collimation target 3, the
direction of the survey instrument main unit 7 is aligned first to
the direction of the collimation target 3 by the rough direction
searching mode. Because the guide light 15 is detected by the
photodetection units 26, 27, 28 and 29 arranged on the four
surfaces of the survey instrument main unit 7, the direction of the
collimation target 3 can be immediately identified from the result
of detection of the photodetection units 26, 27, 28 and 29. At the
maximum rotation of 180.degree., and without rotating further, the
direction of the survey instrument main unit 7 can be turned toward
the collimation target 3 within short time.
[0066] Further, in the precise direction searching mode, the slit
photodetection surface 44 for receiving the guide light 15 is
longer in a up-to-bottom direction. Therefore, even when vertical
angle of the telescope 9 is somewhat deviated with respect to the
collimation target 3, the precise photodetection unit 40 can
perfectly detect the guide light 15. To search the collimation
target 3, it will suffice only to rotate the survey instrument main
unit 7 by reciprocal rotation of for an angle of .+-.45.degree.
only once. When the guide light 15 is detected by the
photodetection element 43, the accurate collimating direction can
be determined, and the collimating direction of the telescope 9 can
be rapidly and accurately aligned to the collimation target 3 as
described above.
[0067] It is needless to say that a normal convex lens may be used
as the cylinder lens 41 in the above embodiment.
[0068] FIG. 10 and FIG. 11 each represents a second embodiment of
the invention.
[0069] In the second embodiment, the vertical angle of the precise
photodetection unit 40 to detect the guide light 15 is further made
larger. In FIG. 10 and FIG. 11, the same components as shown in
FIG. 7 and FIG. 8 are referred by the same symbols, and detailed
description is not given here.
[0070] In the second embodiment, the cylinder lens 50 is different
from the cylinder lens 41 shown in FIG. 7 and FIG. 8 in that the
cylinder lens 41 is curved in an arcuate shape around the focal
point of the lens. That is, the convex surface of the cylinder lens
50 is a part of the rotary curved surface around the focal point of
the cylinder lens 41, and the surface of the cylinder lens 50
closer to the band-pass filter 42 is a part of the cylindrical
surface, which is formed around the focal point of the cylinder
lens 41.
[0071] As described above, the entire cylinder lens 50 is curved in
the arcuate shape around the focal point. As a result, even when
the guide light 15 enters the cylinder lens 50 from any angle in
the vertical direction, the refractive action of the cylinder lens
50 is not exerted as far as it is concerned with the vertical
direction of the beam. Therefore, regardless of the vertical
incident angle of the guide light 15, the guide light 15 is
projected as linear light onto the photodetection element 43.
Accordingly, detection accuracy does not depend on and is not
influenced by the vertical incident angle of the guide light
15.
[0072] The present embodiment is useful in case the collimation
target 3 is placed at a position, which is different in height from
the position of the survey instrument 2.
[0073] FIG. 12-FIG. 14 each represents a third embodiment of the
invention.
[0074] The third embodiment shows a variation of the precise
photodetection unit 40. In this embodiment, the mask 45 in the
second embodiment is replaced with a diaphragm plate 51. On the
diaphragm plate 51, a slit 52 with the same shape as the slit
photodetection surface 44 is formed. The diaphragm plate 51 is
arranged at the focal point of the cylinder lens 50, and the
photodetection element 43 is disposed at a position closer to the
diaphragm plate 51 on the opposite side of the cylinder lens
50.
[0075] By the diaphragm plate 51, the precise photodetection unit
40 detects the guide light 15 within the range of
.+-.1.degree..
[0076] FIG. 15 and FIG. 16 each represents a fourth embodiment.
[0077] The fourth embodiment shows another variation of the precise
photodetection unit 40. That is, it differs from the second and the
third embodiments in the feature that a first front stage diaphragm
53a and a second front stage diaphragm 53b are added. The operation
of the cylinder lens 50, the band-pass filter 42 and the diaphragm
plate 51 is the same as in the above embodiments.
[0078] The first front stage diaphragm 53a is arranged on an inner
surface at an intermediate position of a lens-barrel 49, which
holds the cylinder lens 50, and the second front stage diaphragm
53b is disposed on the end of the lens-barrel 49 on the opposite
side of the cylinder lens 50. The diaphragm plate 51 is arranged at
the position of the focal point of the cylinder lens 50, and the
photodetection element 43 is disposed at a position closer to the
diaphragm plate 51 on the opposite side of the cylinder lens 50.
The band-pass filter 42 is arranged between the second front stage
diaphragm 53b and the diaphragm plate 51.
[0079] The first front stage diaphragm 53a is on the same axis as
the slit photodetection surface 44 and the slit 52 formed by the
mask 45, and it has a slit 54a extending in the same direction.
Similarly, the second front stage diaphragm 53b has a slit 54b.
Each of the slits 54a and 54b has such slit width and length that
the light beam of the guide light from the collimation target 3 is
not blocked when the precise photodetection unit 40 is directed
perpendicularly to the collimation target 3.
[0080] As described above, the width of the slit photodetection
surface 44 is set in such manner that the photodetection range in
the horizontal direction is .+-.1.degree.. When lights enter the
precise photodetection unit 40 from a direction deviated by
.+-.1.degree. of the photodetection range and is reflected by the
inner surface of the lens-barrel 49 or reflected from the inner
portion of the precise photodetection unit 40 and when this lights
are received on the photodetection element 43, they are turned to
disturbance lights, and the S/N ratio is decreased.
[0081] When the disturbance lights enter the precise photodetection
unit 40 beyond the photodetection range of .+-.1.degree. and is
reflected by the inner surface of the lens-barrel 49, the
disturbance lights 30 are cut off by the front stage diaphragms 53a
and 53b. As a result, the disturbance lights 30 do not reach the
photodetection element 43. The photodetection element 43 receives
only the guide light 15, and the S/N ratio is increased.
[0082] Because the front stage diaphragms 53a and 53b are provided,
only the guide light 15 enters the photodetection element 43, and
the S/N ratio is increased and detection accuracy is improved.
Further, the amplification factor of the photodetection signal from
the photodetection element 43 can be set to photodetection
intensity of the guide light 15. This facilitates the setting
procedure and makes it possible to avoid the problem that the
setting should be repeatedly performed.
[0083] FIG. 17 shows a fifth embodiment of the invention.
[0084] In this fifth embodiment, a front stage diaphragm 53 having
a slit 54 is arranged, and a width and a length of the slit 54 are
gradually reduced on the inner surface of the lens-barrel 49. The
slit width and the slit length of the slit 54 are designed in such
manner that the slit matches well with a converging condition of
the guide light 15 and does not cut off the guide light.
[0085] The fifth embodiment provides an effect similar to the
effect when numbers of the front stage diaphragms 53a and 53b are
increased in the fourth embodiment. The reflection lights inside
the precise photodetection unit 40 can be effectively cut off, and
the S/N ratio is increased.
[0086] According to the present invention, when the collimation of
the survey instrument main unit is performed according to the guide
light, it is possible to confirm the collimation target, and to
quickly direct the survey instrument main unit toward the
collimation target. Further, by providing the front stage
diaphragms, it is possible to improve the photodetection S/N ratio
of the guide light, to facilitate the system adjustment, and to
perform collimation of the survey instrument main unit within short
time. In case the survey instrument main unit is ultimately
collimated, collimation can be accurately performed only according
to the photodetection result of a single photodetection sensor of
the precise direction detecting unit. As a result, it is possible
to design the circuit in a simple structure. Because there is the
wide range for the vertical angle, at which the guide light can be
detected by the direction detecting unit, the system can also be
used when there is difference in height between the survey
instrument main unit and the collimation target.
* * * * *